24,174 research outputs found
Nonlinear ER effects in an ac applied field
The electric field used in most electrorheological (ER) experiments is
usually quite high, and nonlinear ER effects have been theoretically predicted
and experimentally measured recently. A direct method of measuring the
nonlinear ER effects is to examine the frequency dependence of the same
effects. For a sinusoidal applied field, we calculate the ac response which
generally includes higher harmonics. In is work, we develop a multiple image
formula, and calculate the total dipole moments of a pair of dielectric
spheres, embedded in a nonlinear host. The higher harmonics due to the
nonlinearity are calculated systematically.Comment: Presented at Conference on Computational Physics (CCP2000), held at
Gold Coast, Australia from 3-8, December 200
Nonlinear ac response of anisotropic composites
When a suspension consisting of dielectric particles having nonlinear
characteristics is subjected to a sinusoidal (ac) field, the electrical
response will in general consist of ac fields at frequencies of the
higher-order harmonics. These ac responses will also be anisotropic. In this
work, a self-consistent formalism has been employed to compute the induced
dipole moment for suspensions in which the suspended particles have nonlinear
characteristics, in an attempt to investigate the anisotropy in the ac
response. The results showed that the harmonics of the induced dipole moment
and the local electric field are both increased as the anisotropy increases for
the longitudinal field case, while the harmonics are decreased as the
anisotropy increases for the transverse field case. These results are
qualitatively understood with the spectral representation. Thus, by measuring
the ac responses both parallel and perpendicular to the uniaxial anisotropic
axis of the field-induced structures, it is possible to perform a real-time
monitoring of the field-induced aggregation process.Comment: 14 pages and 4 eps figure
Numerical study of spin quantum Hall transitions in superconductors with broken time-reversal symmetry
We present results of numerical studies of spin quantum Hall transitions in
disordered superconductors, in which the pairing order parameter breaks
time-reversal symmetry. We focus mainly on p-wave superconductors in which one
of the spin components is conserved. The transport properties of the system are
studied by numerically diagonalizing pairing Hamiltonians on a lattice, and by
calculating the Chern and Thouless numbers of the quasiparticle states. We find
that in the presence of disorder, (spin-)current carrying states exist only at
discrete critical energies in the thermodynamic limit, and the spin-quantum
Hall transition driven by an external Zeeman field has the same critical
behavior as the usual integer quantum Hall transition of non-interacting
electrons. These critical energies merge and disappear as disorder strength
increases, in a manner similar to those in lattice models for integer quantum
Hall transition.Comment: 9 pages, 9 figure
Entropy of the Randall-Sundrum brane world with the generalized uncertainty principle
By introducing the generalized uncertainty principle, we calculate the
entropy of the bulk scalar field on the Randall-Sundrum brane background
without any cutoff. We obtain the entropy of the massive scalar field
proportional to the horizon area. Here, we observe that the mass contribution
to the entropy exists in contrast to all previous results, which is independent
of the mass of the scalar field, of the usual black hole cases with the
generalized uncertainty principle.Comment: 12 pages. The improved version published in Phys. Rev.
Recommended from our members
Exploring resilient observability in traffic-monitoring sensor networks: A study of spatial-temporal vehicle patterns
Vehicle mobility generates dynamic and complex patterns that are associated with our day-to-day activities in cities. To reveal the spatial–temporal complexity of such patterns, digital techniques, such as traffic-monitoring sensors, provide promising data-driven tools for city managers and urban planners. Although a large number of studies have been dedicated to investigating the sensing power of the traffic-monitoring sensors, there is still a lack of exploration of the resilient performance of sensor networks when multiple sensor failures occur. In this paper, we reveal the dynamic patterns of vehicle mobility in Cambridge, UK, and subsequently, explore the resilience of the sensor networks. The observability is adopted as the overall performance indicator to depict the maximum number of vehicles captured by the deployed sensors in the study area. By aggregating the sensor networks according to weekday and weekend and simulating random sensor failures with different recovery strategies, we found that (1) the day-to-day vehicle mobility pattern in this case study is highly dynamic and decomposed journey durations follow a power-law distribution on the tail section; (2) such temporal variation significantly affects the observability of the sensor network, causing its overall resilience to vary with different recovery strategies. The simulation results further suggest that a corresponding prioritization for recovering the sensors from massive failures is required, rather than a static sequence determined by the first-fail–first-repair principle. For stakeholders and decision-makers, this study provides insightful implications for understanding city-scale vehicle mobility and the resilience of traffic-monitoring sensor networks.This research is supported by the Ove Arup Foundation (Digital Cities for Change) and was conducted at the Centre for Smart Infrastructure and Construction (CSIC) at the University of Cambridge
- …